fix(native): keep the active first tab's left fillet past the window buttons

native/cmd/lich-native/topbar.go

@@ -142,7 +142,7 @@ func (t *topbar) layout(gtx C, th *ui.Theme, f topbarFrame) topbarAction {
 	right := t.rightSide(gtx, th, f, &act)
 	left := t.leftSide(gtx, th, f, &act)
 	f.brandWidth = max(f.brandWidth-left, gtx.Dp(brandHeight))
-	start := max(f.stripX, g+left+f.brandWidth+gtx.Dp(barGap))
+	start := stripStart(f.stripX, g+left+f.brandWidth+gtx.Dp(barGap), gtx.Dp(tabRadius))
 	t.shift, f.stripX = start-f.stripX, start
 	t.place(gtx, image.Pt(g+left, 0), func(gtx C) D { return t.brandButton(gtx, th, f) })
 	stripW := gtx.Constraints.Max.X - right - g - gtx.Dp(barGap) - f.stripX
@@ -153,6 +153,16 @@ func (t *topbar) layout(gtx C, th *ui.Theme, f topbarFrame) topbarAction {
 	return act
 }
 
+// stripStart is where the tab strip starts: at the island's edge, or, when
+// the window's own buttons and the brand reach past it, a fillet radius after
+// them, the room the active first tab's left fillet draws in.
+func stripStart(islandEdge, brandEnd, radius int) int {
+	if brandEnd <= islandEdge {
+		return islandEdge
+	}
+	return brandEnd + radius
+}
+
 // place lays w out at p.
 func (t *topbar) place(gtx C, p image.Point, w layout.Widget) {
 	defer op.Offset(p).Push(gtx.Ops).Pop()

native/cmd/lich-native/topbar_tabs.go

@@ -111,7 +111,13 @@ func (t *topbar) strip(gtx C, th *ui.Theme, f topbarFrame, act *topbarAction) D
 		ids[i] = tab.ID
 	}
 	size := gtx.Constraints.Max
-	clipped := clip.Rect{Max: size}.Push(gtx.Ops)
+	// A strip pushed past the island's edge reaches left over the room
+	// stripStart left, where the active first tab's left fillet draws.
+	var filletRoom int
+	if t.shift > 0 {
+		filletRoom = gtx.Dp(tabRadius)
+	}
+	clipped := clip.Rect{Min: image.Pt(-filletRoom, 0), Max: size}.Push(gtx.Ops)
 	tabs := t.list.Layout(gtx, 1, func(gtx C, _ int) D {
 		return layout.Flex{Alignment: layout.Middle}.Layout(gtx,
 			layout.Rigid(func(gtx C) D {

native/cmd/lich-native/topbar_test.go

@@ -96,3 +96,16 @@ func TestSettingsButtonOpensOnGlobalAfterAProjectScope(t *testing.T) {
 		t.Errorf("the settings button opened on scope %q (open %v), want Global", u.settings.scope, u.settings.open)
 	}
 }
+
+// Past the window's own buttons, the strip leaves the active first tab's
+// left fillet a radius of room after the brand, where it would otherwise be
+// cut off at the strip's edge.
+func TestStripStartLeavesTheFilletRoom(t *testing.T) {
+	const island, radius = 44, 8
+	if got := stripStart(island, 40, radius); got != island {
+		t.Errorf("brand short of the island: start %d, want the island's edge %d", got, island)
+	}
+	if got := stripStart(island, 120, radius); got != 120+radius {
+		t.Errorf("brand past the island: start %d, want %d", got, 120+radius)
+	}
+}